Sinking Objects
Floating and Sinking: Sinking Objects
Sinking Objects
Sinking Objects
NCERT anchor
Looking Around 2 — simple sink-and-float play activities with a tub of water and classroom objects.
What you'll learn
- Some things sink in water — they go down to the bottom.
- Sinking things are usually heavy for their size, like metal and stone objects.
- Examples of things that sink: a small stone, an iron nail, a coin, a metal key, a steel spoon, a glass marble, a small rock, a metal bolt, a brass ring, a steel ball.
Key concepts
Verbal: An object that goes down to the bottom of the water is sinking.
Level 1 — Things that sink
| Object | Why it sinks |
|---|---|
| Small stone | Heavy for its size |
| Iron nail | Iron is heavy for its size |
| Coin | Metal is heavy for its size |
| Metal key | Metal is heavy |
| Steel spoon | Steel is heavy |
| Glass marble | Solid and heavy, no trapped air |
Level 2 — No trapped air
Sinking objects usually have no air trapped inside them — they are solid all the way through.
Worked example
You drop an iron nail into a bucket of water. What happens?
Step 1 — The nail is heavy for its size and has no trapped air.
Step 2 — It goes straight to the bottom.
Answer: The nail sinks.
Common mistakes
| Mistake | Why | Fix |
|---|---|---|
| Small things always float | Confusing size with weight | A small coin still sinks |
| Shiny things always float | Confusing shine with lightness | A shiny steel spoon still sinks |
Quick check
- Name three things that sink in water.
- Why does an iron nail sink?
Stretch: Will a metal spoon ever float? Why or why not?
Revision tip: Drop a coin, a key, and a cork into a bucket of water and watch what happens.
Open the Practice tab for graded questions on Sinking Objects.
Key Takeaways (TL;DR)
- NCERT anchor
- What you'll learn
- Key concepts
- Worked example
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